1. Field of the Invention
The present invention relates to a thin film transistor array panel and a method of manufacturing the same.
2. Description of the Related Art
A thin film transistor (TFT) array panel is used as a circuit board for independently driving each pixel in a liquid crystal display or an organic light emitting diode display (OLED). The thin film transistor array panel includes, for example, gate lines that transmit gate signals, data lines that transmit data signals, thin film transistors that are connected to the gate lines and the data lines, and pixel electrodes that are connected to the thin film transistors.
The thin film transistors are switching elements that control the data signals transmitted to the pixel electrodes through the data lines according to the gate signals transmitted through the gate lines. In addition, the thin film transistors include gate electrodes connected to the gate lines, semiconductor layers forming channels, source electrodes connected to the data lines, and drain electrodes facing source electrodes with respect to the semiconductor layer.
However, several photolithography processes are required to manufacture the thin film transistor array panel. Since each photolithography process has complicated sub-processes, the required time and cost for manufacturing the thin film transistor array panel are influenced by the number of photolithography processes.
One of the photolithography processes can be eliminated by simultaneously forming the connection structure of the drain electrodes and the pixel electrodes, the pixel electrodes, contact holes for connecting the gate lines and the drain electrodes to external driving circuits, and contact preliminary members.
When such thin film transistor is manufactured, a contact hole and an opening portion are formed by forming a passivation layer on the data lines and the drain electrodes, forming a photoresist layer on the passivation layer and etching the passivation layer by using the photoresist layer as a mask. A transparent conductor layer may be deposited without the removal of the photoresist layer. However, if the photoresist layer is removed, the photoresist layer and the transparent conductor layer disposed on the photoresist layer are simultaneously removed. Then, the remaining transparent conductor layer becomes a contact assistant member and a pixel electrode.
In the above-described lift-off method, when the contact holes and the opening portions are formed on the passivation layer, since the data lines and the drain electrodes exposed through the contact holes and the opening portions are simultaneously etched, short circuits and poor contacts may occur. Accordingly, a photoresist layer having a gentle inclination is required so as to form the contact hole and opening portion. However, it is difficult to completely remove the photoresist layer without leaving a residue.